1. Field of the Invention
The present invention relates generally to the cleaning of residues and by-products from substrate surfaces and, in particular, to removing residues and by-products from electronic component substrates, such as integrated circuits and semiconductor wafers, and adhering such removed residues and by-products to interior surfaces within a processing chamber.
2. Description of Related Art
The fabrication of electronic components such as integrated circuit semiconductors is very exacting and complex and requires a number of processing steps requiring extreme precision to form the desired circuit pattern on the component substrate. Typical semiconductor devices now have circuit line widths typically less than 0.5 micron with close spacing of the lines and via interconnections. Contamination of the semiconductor substrate in the form of particles on the substrate surface may cause short circuits, open circuits and other defects, which can cause the component to fail and/or adversely affect the performance of the component. For example, an individual particle as small as 100 angstroms in diameter can result in a defect in a modern microcircuit electronic component.
Cleaning the surface of the semiconductor substrate is therefore a critical step in integrated circuit fabrication. There are currently numerous methods used to clean substrate surfaces in the electronic industry. Water, solvents or chemical cleaning agents or gases are often used to remove contaminate particles and films from the surfaces. For example, gas jet cleaning and liquid spray cleaning are used to clean relatively large particles from silicon substrates.
Cleaning is also used to remove native metal oxides when clean virgin surface is required, which is the case for preclean prior to conductive materials deposition on top of other conductive layers, such as for physical or chemical vapor deposition of electrically conductive materials.
Sputtering is another technique for cleaning both large and small particles from substrate surfaces. Sputter cleaning of a substrate involves bombardment of the surface with argon or other types of gas ions for the removal of oxide and/or nitride films, and thereby improve the adhesion of subsequently deposited material layers to the substrate surface. During the sputter cleaning process, by-products, residues and particles are removed from the substrate surface and deflected towards the interior components of the sputter chamber, such as shields, as well as towards the interior sputtering chamber walls. These by-products, residues and particles adhere to both the interior sputtering chamber components and the interior chamber walls.
As these by-products, residues and particles are sputtered, they adhere to the chamber components and interior chamber surfaces in a non-uniform manner. Due to this non-uniform nature of adherence, the deposited by-products, residues and particles have relatively poor adhesion to the chamber walls and components since the areas of contact and bonding between deposition and the chamber walls and components are small. As sputtering continues through a number of wafers, more of these by-products, residues and particles are deposited on the chamber components and interior surfaces. As the thickness of deposition increases, the deposited by-products, residues and/or particle nodules grow and start touching each other. However, rather than forming a continuous coating or film, upon contact of these by-products, residues and/or particle nodules with each other, the nodules crack and break-off due to the low ductility, falling onto the semiconductor wafer being processed. It is these particles falling onto the semiconductor surfaces that damage the semiconductor and ultimately lead to device failure. One root cause of particle failure is believed to be due to poor adhesion of by-products to the chamber components and interior surfaces due to small areas of contact and bonding.
Prior art has focused on increasing the surface area of the chamber components to improve adhesion. For example, prior art is directed at the use of high surface area coatings on chamber components, such as aluminum arc spray, alumina or zirconia plasma spray, to solve the problem of material delamination from shield substrates in etch modules. However, such practices do not significantly improve material delamination, such that these procedures are not sufficient for practical production and manufacturing purposes.
Wafer contamination continues to be a problem in the electronics and semiconductor fabrication industry. As the industry advances and technology is being developed to form smaller and more complex circuits, a more effective and efficient cleaning method to remove by-product, residue and particulate foreign matter from substrates, and preventing such removed foreign matter from damaging the substrates, is required to produce electronic and semiconductor components.